Project Summary The goal of this application is to translate our discovery of an unsuspected mechanism of mucus pathology into a mucolytic drug strategy that could benefit millions of patients with mucus-associated lung disease. Specifically, we have discovered that mucus elasticity in CF results from neutrophil oxidant stress that cross- links mucin polymers to stiffen the airway mucus gel. Because oxidative stress occurs in multiple situations associated with inflammation and environmental exposures, we hypothesize that oxidative stress is a ubiquitous and previously unsuspected cause of increases in mucus elasticity in disease. This provides rationale for developing mucolytic drugs with wide clinical utility that can cleave disulfide bonds as a mechanism of action. Our tPPG group has synthesized novel thiol-modified carbohydrate compounds (?thiol- saccharides?) and shown them to have potent mucolytic activity in CF sputum. We have encouraging preliminary data for their formulation as dry powders and reassuring data regarding their safety. We now propose three projects supported by two cores to bring a thiol-saccharide to the clinic as a new treatment for CF and other mucus-associated lung diseases. Project 1 will modify carbohydrate scaffolds to create a library of synthetic mucolytic compounds, conduct lead optimization studies, and formulate thiol-saccharides for delivery as dry powders. Project 2 will screen the mucolytic efficacy of thiol-saccharide library to aid in identification of lead compounds and the preclinical candidate compound and will identify a sub-population of asthmatics who may benefit from mucolytic treatment. Project 3 will progress the lead thiol-saccharides to a preclinical candidate and then to the clinic as a novel mucolytic strategy for mucus pathology in cystic fibrosis. Cores A and B will provide all three projects with support in areas of administration, finance, communication, data management and integration and human subjects. Our proposal is timely and highly clinically relevant, and it is supported by strong preliminary data and high promise for realizing our goal. PHS 398/2590 (Rev. 06/09) Page Continuation Format Page